Method and system for solid particle removal

ABSTRACT

Disclosed is a system and method to separate solid particle components from a fluid. It can be used in close association with a hydrocarbon producing well and uses a novel combination of mechanical filtration, solids decantation, and real and apparent forces. Disclosed is a spherical vessel with a tangential inlet to introduce the fluid and a fluid exhaust and filter arranged on the center line of the interior of the vessel. A combination of pressurized fluid and solid particles enter at the tangential inlet and move primarily in a circular path around the interior of the vessel. The circular path results in the larger mass particles settling at the vessels lower region. Less massive particles may be entrained in the exiting fluid flow toward a filter element where they are removed from the exiting fluid. The vessel has an opening to remove the trapped separated particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/US2018/014106; which claims the benefit of U.S.Provisional Application No. 62/618,325, filed Jan. 17, 2018, and thebenefit of U.S. Provisional Application No. 62/447,749, filed Jan. 18,2017; the entirety of all which are incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to separators used in oil and natural gaswell completion and production operations and, more particularly, togenerally spherical separators particularly suited for use in separatingsolid material from high pressure, high velocity fluid streamsencountered at hydrocarbon wellheads or equivalent.

BACKGROUND OF THE INVENTION

For over 100 years oil and gas extraction from hydrocarbon-richsubterranean locations has been performed predominately via chipping,drilling or other means in a vertical hole in the earth surface toaccess oil and gas rich regions. These hydrocarbons have been criticalin economic and technical advancement throughout modern civilization andprovide energy, transportation fuel, and chemical precursors forfertilizer, materials, pharmaceuticals and a myriad of other chemicalsand technologies.

However extracting hydrocarbons has become more difficult and moretechnical as drillers are required to reach deeper and more difficultreserves and to deliver greater quantities of hydrocarbons from eachreserve. Advanced methods to increase extraction include chemical meanssuch as surfactants and solvents in injector wells and Steam AssistedGravity Drainage or SAGD to name two of several. In addition, many wellsuse the technique of the horizontal drilling, wherein the drilled wellbore or hole, after having been drilled vertically thousands of feet toreach oil-rich strata, will be further drilled substantiallyhorizontally, developing a well bore or hole in the horizontal strata.

Additional methods include mechanical and chemical techniques such ashydraulic fracturing. Hydraulic fracturing or fracking involvesinjecting a large quantity of high pressure fluid and solid particlemixture into the well, opening existing fissures and fractures and evenpossibly creating new fissures and fractures, thereby increasing thevolume of oil or gas from each well, or to make existing wells producefor longer periods of time.

Generally, these oil, oil and gas, or gas wells, which may be enhancedby hydraulic fracturing produce not only oil and gas but also water,other liquid impurities and particle solids called collectively a fluidstream. The source of the undesirable solids contamination may be fromthe hydrocarbon-rich rock formation itself or by added materials such asfracturing proppant, for example ceramic spheres or sand. The dimensionof the solids will be variable, from high diameter particle and particleaggregates which can nominally be larger than 0.1 inch diameter, to verysmall diameter particles and particle aggregates, which can be less than0.005 inch diameter. The proppant is generally used in conjunction withlarge volumes and pressures of additive containing liquids to expandexisting fractures in the formation, and to “prop open” the fissures.The liquids additives are chosen with the objective, among other things,of increasing the viscosity of the fluid so it will better transport theproppant to the end of the fracture. Once the fracturing process iscompleted, at least a portion of the additive containing liquid or gasor a combination will return through the well bore back to the wellhead,usually under high pressure. Whether the material originated from thehydrocarbon-rich rock formation or from solid materials such as varioustypes of proppants, they are referred to herein as “sand” or “solidparticle components” unless otherwise specified.

The combination of solid particle components with a fluid stream,especially under high pressure, will cause surface erosion ordeterioration in oil and gas well components such as wellheads, valves,fittings and the like. Erosion caused by the presence of the solidparticle components in the fluid stream can cause equipment damageincluding system failure. System failure can cause massive loss ofproperty and even human life. In addition, these solid particlecomponents also contaminate further processing and can cause significantequipment deterioration over short periods of time.

Sand separating systems, in general, exist to separate solids and solidparticle components from a liquid stream or from a gas stream or from acombination of a liquid and gas stream and will be referred to as afluid stream to describe any combination of gas, oil, water and solids.The systems may be spherical, cylindrical or conical or a combination ofcylinder and cone, most often oriented with the long axis of the systemin the vertical direction. The dimensions of a conventional fluid andsolid separation system are chosen to allow the fluid stream to undergoa sufficiently large velocity drop to facilitate solids removal beforethe fluid stream exits the separator. In some separator systems, animpact plate maybe added internally for the high velocity solids andfluid to impinge.

Historically, these predominately cylindrical or conical separatorsystems have been effective when the inlet fluid stream has asubstantially low velocity and a relatively low fluid flow rate.Additionally, the fluid stream usually has had low fractions of solidparticles to overall volume of fluid and said solid particle componentsare substantially of the same dimension. In the case of added particles,such as for hydraulic fracturing, the particle diameter is selected tobe appropriate for a given well. At higher fluid velocities, and greaterdistribution of the solids dimensions, these conventional separatorssignificantly lose the efficiency of the solid separation. These systemsare not suited to high velocity fluid streams containing large amountsof variably sized sand and water compositions that are most oftenencountered at or near the wellhead. The higher the velocity of incomingfluid and the smaller the solids sizes, the greater the relative dragforce on the moving fluid and particles. In this high velocity, smallparticle sized environment, the standard separator will not functioneffectively and will not remove a large fraction of the solids.

For a conical or cylindrical sand separator to work safely at pressuresin excess of 10,000 psi, the wall thickness of the separator, forexample, can be steel more than 3 inches thick. Thus, the size, weight,material and cost of such a system becomes impractical, difficult tomanage and cost prohibitive.

A system that can effectively separate a wide range of solid particlesizes from a high volume, high velocity stream in a smaller and lighterpackage, made with less expensive material is needed in the industry.The separator system of this invention solves these historicalshortcomings.

SUMMARY OF THE INVENTION

We describe a vessel whose interior and associated piping, tubing,flanges, fittings and filters are used to separate solids from a fluidstream. The fluid can be various liquids or various gases or liquids andgases together. The vessel and its associated sub-systems are installedin relatively close proximity to an oil or gas well exit known as awellhead and are thusly exposed to at or near maximum pressure of thewell. The invention is constructed to utilize a combination of real andapparent mechanical forces including gravitational and centrifugal, aswell as from time to time, and if required, mechanical filtration toseparate solid particle components from fluid. The previously mentionedforces, separator device and mechanical filtration when required, willcause the larger solids to deposit and remain at the bottom of theinterior volume of the vessel and also, if used, the filter will removesome remaining smaller particles, and will cause the exiting fluid to besubstantially free of solid particles. The presence or absence of thesubsequent mechanical filter should not typically be limiting and oneskilled in the art will recognize that the preponderance of filteringoccur within the enclosure of the sphere. The combination of theseparation techniques allows the system to handle a wide range of solidsizes, a wide range of fluid constituents, and the efficiency of theseparation will be less sensitive to the fluid velocity.

The solid particle separator has predominately a spherical interiorvolume. The exterior may also be spherical but may be other geometriesas is warranted by the specific use, by fabrication techniques, and willbe recognized to one skilled in the art to have no bearing to theinterior surface, function or volume. In addition, the interior could bea geometry that is smooth, regular and wider in approximately thecentral region and narrower at the non-equatorial regions including suchgeometries as elliptical and smooth double conical. In addition, alldiameter transitions are smooth and regular. The conventional locationfor installation and use is at or near the wellhead of an oil or gaswell but this should not be limiting, as the separation effect isindependent of placement.

The solid particle separator may be installed as a single separator, orany number of separator systems may be used, with two in parallel as aconventional configuration, but many arrangements of separators may beused and the specific arrangement of separators is not a limitation andone skilled in the art will recognize this. The inlet port is arrangedaround the horizontal plane and is conventionally located slightly abovethe sphere of the separator equator or midplane and tangential to theinterior surface of the sphere. This allows the inlet fluid and solidsmixture to travel in a roughly disc-shaped flow pattern upon entrance tothe interior region of the separator. The angular velocity of themixture is in part determined by the inside diameter of the interiorregion at the inlet height and the velocity and also viscosity of anyintroduced fluid.

While the invention is generally described to be placed after ahydrocarbon wellhead, a wellhead can mean any source of fluid includingan oil well, a gas well, a mechanical pump exit or any source of fluidsthat can be input to the device.

A particle that enters predominately tangentially into the sphere willbe subjected to a variety of real and apparent forces including but notlimited to:

-   -   Gravitational force insomuch as the particle will have only        horizontal velocity, the weight of the particle will cause it to        move substantially out of the horizontal plane and to begin        moving to the lower portion of the sphere;    -   Centrifugal force insomuch as the fluid and particles entering        the sphere, substantially tangentially, will have angular        velocity of the particle which will cause a centrifugal force        that will move the particle to the wall of the sphere; upon or        after the particle makes contact with the inner spherical        surface, it will be caused to slide downward following the        expanding slope of the wall, as the initial plane of rotation is        predominately above a horizontal mid-plane; and    -   Coriolis Force insomuch as the angular movement in a horizontal        plane may cause an apparent force exerted on the particle, which        will affect the particle in a downward direction.

It will be recognized to one skilled in the art that the name anddescription of the forces, and to what amount each has action on theparticle is in no way limiting to the scope of the invention.

The solid separator system is comprised of an interior volume that ispredominately spherical which is alternately known as an ellipsoid ofrevolution with a single focus, but it can also be an ellipsoid ofrevolution with two foci or a non-ellipsoidal oval of revolution or acombination of smooth conical features with ellipsoidal or sphericalfeatures. When the interior is described as spherical it will berecognized by one skilled in the art that it is a range of shapes fromspherical to an ellipsoidal volume to an oval volume with the generalfeature that the center is larger than the poles.

The solids that are removed from the fluid can be native sand from theformation or fracking sand or fracking proppant in the form of, forexample, ceramic particles, or drilling cuttings or other solid particlecomponents that have been added as part of the development of a well orthat are naturally occurring in the region prior to drilling or acombination of the two. In addition, these solid particle components maybe singular particles or may agglomerate as composite particlesconnected by chemical means, electrostatic means, a combination, orother means. This configuration of solid materials entrained in a fluidas referred to hereinafter as solid particle components, and one skilledin the art will recognize that these descriptions should not belimiting, and any entrained solid particles or solid agglomerates willbe referred to as a particle or collectively as particles. Also in thiscase fluid refers to liquid such as water, oil or other liquidsencountered at the well, and to gases such as naturally occurringmethane, added carbon dioxide or other non-liquid, non-solid materials.Fluid can also refer to sublimed materials.

Once the fluid and solids in the form of particles or particleagglomerates or other configurations of solid materials that areentrained in a fluid flow emerge from the wellhead they enter theseparator via an entrance port or tube that is located slightly abovethe mid-plane of the interior sphere volume and is located tangentiallyto the interior surface of the sphere volume.

Once the high-pressure fluid and particles are introduced tangentiallyinto the volume of the separator, the fluid and particles are in apredominately circular path. The said forces will cause said solidparticles to move in a substantially radially outward and downwarddirection.

The particle, becoming proximate to the interior surface of theseparator, will migrate to the lower section of the sphere due to one ormore effects of forces exerted on the particle.

Some particles may remain entrained in the fluid flow and can beseparated from the exiting fluid by means of additional filters throughwhich all exit fluid traverses.

The fluids exit is substantially at the center top of the separationdevice. The moving fluid and any entrained solids will leave the spherethrough said exit. The solids that are acted upon and moved by the fluidto the center of the sphere, will be filtered with a dedicated filterthat can be internal to the sphere or external to the sphere with thepreferred embodiment having the filter external to the sphere. The fluidtransporting the still entrained solid particles will impinge upon andtransit through the filter.

In general, said filter is of cylindrical construction with the longaxis arranged to be collinear to the fluid flow direction. Typically,the fluid transits through the surface of said filter device. Said fluidcan transit either from the interior surface outward or from theexterior surface and move inward. Said filter can be located in avariety of locations with no change to the operation of the invention orto the invention. Said filter can be contained within the interior andgenerally arranged more or less on the polar axis extending from oneinterior surface to the interior of the sphere of the sphericalseparator or is further contained in a structure that is of largerinternal diameter than the external diameter of said filter element andis operated outside of the separator. Further, separator can be usedwith or without the filter elements.

The input port that allows the high pressure, high velocity stream ofmaterial to be introduced into the interior volume of the separator ismost often arranged slightly above the mid-plane and is locatedtangentially to the interior surface. This allows the high-pressurecombination of fluid and solids to be launched in a trajectory slightlyabove the mid-plane. However, the input may be at or below the midplane.

The sections of the separator device can be joined using a variety oftechniques common to metal fabrication including using weldingtechniques to permanently connect the portions of the sphere that havebeen forged, machined or otherwise constructed. Also, the separator canbe constructed using bolts, flanges and the like to join the variousportions of the separator body. In addition, if the device is made intwo sections, those two sections can be connected by using threads. Oneskilled in the art will recognize that the methods, if any, to connectthe separator will not limit its use, or operation or function. Inaddition, if a filter is to be connected, it may be connected usingthreaded mating components but one skilled in the art will recognizethat the filter can be affixed using one or more of several meansincluding threads, bolts, flanges, mounts, keepers and the like and thisis not a limitation of the invention.

The invention is designed with materials and techniques to allow it tobe used at wells, wellheads and other sources of fluids and pressures.The invention can be used with pressures from a few hundred psi topressures in excess of 20,000 psi. In addition, the device can be sizedto most appropriately accommodate the range of pressures, viscosities,and solids encountered. The internal volume can range from sizes smallerthan 10 cubic feet to sizes larger than 40 cubic feet. The specific sizewill be chosen to best function with incoming pressures andcompositions. Also, the inlet port dimensions are chosen to alsoaccommodate incoming pressures and compositions, in addition to theexisting fitting, tube and pipe size encountered at point of use. Commonsizes of inlet port sizes are smaller than 0.5 inches to larger than 5inches. The inlet port offset can also be chosen to best accommodate thepressures, viscosities, chemistries, and solids encountered at the pointof use. Common offsets can be smaller than 0.5 inch and more than 10inches. Both the lower and upper ports can be a range of sizes toaccommodate the pressures, flows, solids content and other parameters.Common port sizes can range from smaller than 1 inch to larger thanflinches.

The invention can be used in parallel to increase throughput or toeffectively decrease pressure in each unit and the invention can be usedin series with either identical devices or differently sized devices tomaximize filtration efficacy and this is not a limitation.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the present invention maybe set forth in appended claims. The invention itself, however, as wellas a preferred mode of use and further objects and advantages thereof,will best be understood by reference to the following detaileddescription of an illustrative embodiment when read in conjunction withthe accompanying drawings, wherein:

FIG. 1 shows in schematic the invention with a single sphere.

FIG. 2 shows in schematic the invention with two separators, operated inparallel, attached to a single wellhead and a plurality of valves.

FIG. 3 shows a side view of the separator with the inlet both above thecenter plane and tangential to the vessel interior.

FIG. 4 is an additional view of the entrance port showing its tangentialentry and the location above the mid-plane of the separator includinginput flange with through holes and central opening port.

FIG. 5 is a top-down cross section view of the separator with the portshown to enter substantially tangentially to the interior region.

FIG. 6 is a is a schematic of a particle path internal to the separator.

FIG. 7 shows a bevel or chamfer to facilitate joining portions of thesphere together using butt welding.

FIG. 8 shows an idealized plot of angular momentum versus the radialdistance from the chamber center.

FIG. 9 shows a detail of the filtration unit.

FIG. 10 is a detail of cross section of separator including location ofrecovered sand.

FIG. 11 shows detail of the filtration unit.

FIG. 12 is a schematic of potential real and apparent forces on a sampleparticle including gravitational, centrifugal and Coriolis.

FIG. 13 shows the separator, two external filters and a plurality ofvalves.

DESCRIPTION OF A PREFERRED EMBODIMENT

While the invention has been particularly shown and described withreference to preferred and alternate embodiments, it will be understoodby those skilled in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinvention.

The apparatus of this invention is designed to separate particle solidcomponents from high pressure, high velocity fluid streams. As usedherein, fluid and fluids shall be understood to be the non-solid portionof the material entering a separator and can be comprised of liquids andflowback fluid like water, brine, solvents, surfactants and hydrocarbonsand can be exiting gases like naturally occurring natural gas, or anadded gas added to the well either in liquid phase or gas phase such asa fracking or flowback additive or aid or other material, and all suchvariations are contemplated to be found within the invention's operatingspecifications. As used herein, solid particle components shall beunderstood to be solid phase materials and aggregates that are entrainedby the movement of the fluid entering the separator. Said fluid iscomprised of water, chemicals, gases and solids. The device is designedto handle the high flow, high velocity and high-pressure fluid and solidstreams while maintaining effectiveness at separation of solidparticles. During continued operation, the composition of the fluidentering the separator may change from a fluid comprised ofpredominately liquid based constituents with minimal gas components tosubsequently a fluid stream comprised of a predominately gas fluid withlower quantities of liquid entrained in the fluid transport.

Under high pressure or high fluid flow or both, solid particlescomponents are entrained in the fluid flow, and travel substantiallywith the flow of the high pressure and high velocity fluid. Theparticles may have an overall velocity that is less than or greater thanthe average fluid flow velocity. This untreated and un-separated flow offluid and solids can cause substantial damage and erosion on interiorsurfaces of equipment. One having ordinary skill will recognize that themajority of the entrained solids are fracking proppant and naturallyoccurring formation particles and all such variations of particlecomposition are contemplated to be found within the present inventionsoperating environment. The invention can work with all pressuresconventionally encountered at wells but if future well pressures arefound to be greater, the invention will be expected to work at greaterpressures. In addition, the device can be expected to work at lowerpressures as well. There is a general relation between incoming pressureand vessel size.

This invention comprises a vessel having an internal generally sphericalregion or cavity that will allow a high pressure and high velocity fluidand solid particle stream to enter said interior cavity. In anembodiment, the vessel is known as a separator. Unlike other solidparticle separators, this device does not use any baffles or deflectionplates or other additional means to reduce fluid and particle velocity.This separator uses natural fluid flow and the principles associatedwith angular momentum and other real and apparent forces to separateparticles from a fluid stream.

Referring to FIGS. 1-12, the present invention comprises a solidparticle component removing device that separates solid material from afluid stream, herein called a separator, installed in proximity to anddownstream to a wellhead and upstream from other support equipment suchas a choke valve manifold, or other in-line equipment. The solidparticle component separator causes solid particles and particleaggregates from a fluid stream including a high-pressure high-velocityfluid stream to migrate to substantially lower regions in the separatordevice. Particles with a mass greater than a threshold amount arecollected in the bottom of the device and said collected particles canbe removed or extracted by means of a removal port, valve, device orschema generally on the bottom of the device. Any particles that remainentrained in the fluid flow may be separated by means of a mechanicalfilter external to the body of the separator.

Valves throughout this invention are generally included in pairs tofacilitate the efficient isolation of sections of the device to changefilter elements, change separator devices, to remove sand and otherparticles and to facilitate the aforementioned changes and otherswithout causing the well to be closed or shut-in or for high-pressurefluid or solids to exit the system in an uncontrolled fashion however inno way should they be inferred to be a limitation on invention and aresimply included as one non-limiting embodiment.

FIG. 1. shows the separator device 10 including inlet port flange orconnection surface 11, the inlet tube or pipe 12, with penetration intosphere 13. In addition, solids removal or outlet tube and port flange 14and fluid exit flange 15.

Predominately following a wellhead and associated hardware, the solidparticle component separator removes a large mass range of solidsincluding those removed by means of mechanical and apparent forces,higher angular momentum and gravity, and those lighter solids removed bymechanical filtration.

FIG. 2 shows, schematically, multiple separators used in parallel and aplurality of connection and isolation valves. Two separators areindicated but one skilled in the art will recognize that any number ofseparators can be used. Incoming fluid and solids are introduced throughinlet 20 and through manifold 21, allowing multiple separators to beused. Separators can be isolated by valves 22 and 22′, 23 and 23′ andalso 24 and 24′, all of which can shut off the incoming or exitingmaterials to facilitate servicing, adjustment or replacement and furthercan isolate said separator allowing service or use of and alternateseparator. Port 13 is substantially at or above the mid-plane 25. Onewill also recognize that any effective number of separators can bearranged in series, in parallel or a combination of series and parallel,and that the specific number in use is not a limitation as well as thevalves, fittings and flanges are simply one embodiment and should not beconstrued as limiting

Prior to fluid entering said separator, there can be a plurality ofvalves, manifolds and associated equipment conventionally found atwellheads including schematically shown manifold 21, valves 22, exitvalves 23 and exit manifold 25. The inclusion or omission of anyassociated equipment other than the invention herein should berecognized by one of ordinary skill in the art to not change theinvention or use. Valve 22 serves to route or control flow of fluid toseparator. One having ordinary skill in the art will recognize thatvalves 22 and 22′ are representative in nature and there areconventionally additional wellhead equipment between the wellhead andthe separator and the valves 22 and 22′ is not intended to represent acomplete installation but merely to illustrate that the separator can beisolated as required.

Solids can be removed by opening valves 24 and 24′, most often whenvalves 22 and 22′ and 23 and 23′ are closed to allow the removal ofsolids with no associated high well pressure. In addition, FIG. 2 showsupper filter isolation valves 27 and 27′, external filter 28 and lowerfilter isolation valves 29 and 29′. The inclusion of an external filteris one embodiment and should not be construed as limiting, as theinvention can be used with or without a filter and the filter, if usedcan be internal or external.

FIG. 3 shows inlet port flange 11 which allows the connection of asource of fluid and solids into the interior of the separator via theinlet tube 12 and penetrating into interior of separator through inlettube hole 13. Solid material that has been separated can be removedthrough separator sphere opening 32 and continuing through bolt surface33. Separator sphere 34 has both an interior surface 35 and exteriorsurface 36. Separator has a mid-plane 37, of which the inlet portcomponents 11, 12 and 13 are at or substantially above. Upper boltsurface 38 is a surface to mount additional manifolds and otherapparatus through which the pressurized fluid may exit the device. Thespecific mounting schema may comprise a machined mounting surface andbolt holes, a tube and flange system or other connection methods andshould not be construed as a limitation.

In addition, said separator comprises a high pressure, high fluid volumevessel. Said separator comprises an outer surface 36 and an innersurface 35 that can be spherical, nearly spherical, elliptical, oval orother geometries where the region near or about the midplane is ofgreater diameter than those areas closer to the upper and lower portpenetrations. One skilled in the art will recognize that the surfacegeometry does not materially affect the separator function. Requiredpenetrations comprise an inlet port system 11, 12 and 13 to introducehigh pressure high volume fluid and solid particle components into theseparator, a fluid exit bolt surface 38 and fluid exit penetration 39 aswell as a collected particle extraction port 32 and mounting surface 33.Other penetrations could include but are not limited to pressure sensingports, fluid velocity sensing ports, and particle level detection ports,none of which are material to the operation of the separator.

Separator vessel 34 is constructed of such materials and by suchprocesses that will provide suitable structural integrity to withstandthe range of pressures expected, as well as in excess of those pressuresat a wellhead, without requiring systems or equipment to reduce incomingpressure such as chokes and other means, which are frequentlyencountered on other types of separators and significantly limit theiruse and said pressure restriction can damage a well. Separator inputsystem 11, 12 and 13 are substantially tubular and substantiallyhorizontal with respect to the midplane of the separator. The separatorinput is more or less tangential to the interior of the sphere.Separator input is substantially arranged at or above the midplane 37 ofthe separator. The input tubular structure 12 extends from the body ofthe separator 34 to a distance that will allow convenient connection toassociated well hardware. The input 11 is of a sufficient diameter toallow sufficient flow and material velocity within the separator toachieve separation. Tube 12 inside diameters can range from a fractionof an inch to several inches with an inside diameter of 2 inches being acommon size.

Solids removal penetration 32 at the lower section of the separatorallows solid particle components removal and disposal after a suitablequantity has been collected. Said solids collected may be comprised ofdry particles or may be comprised of solids and liquids, a slurry orother collected materials prior to extraction. Collected solid materialrefers to those particles that have come substantially to rest in thelower portion of the separator and are not in substantial motion, thoughto one skilled in the art it will be clear that some degree of solidsmotion is possible and does not change the operation of the device.Alternately the lower portion of the vessel can comprise a schema forthe continuous or semi-continuous removal of solids from the separator.To one skilled in the art, it will be apparent that the inventionremains substantially unchanged in either embodiment and is not alimitation.

One preferred embodiment has dimensions as follows but one skilled inthe art will recognize the dimensions can be changed with no adversechange in the functionality of the separator. In addition, onerepresentative embodiment is described but should not be a limitingfactor as other dimensions will be equally effective. The inlet port 11from FIG. 3 is approximately 3 inches above the horizontal midplane. Theexterior radius is substantially 23 inches and the internal radius isapproximately 20 inches. The initial surface of the fluid inlet is 26inches from the centerline. The separator is approximately 50 inchestall from surface 33 to surface 38 on the central vertical axis,including built up areas for fittings. The central bore of the inlettube is about 19 inches from the midplane. The upper fixturing surfacebuilt up region is approximately 14 inches in diameter and the lowerfixturing built up region is approximately 8 inches diameter.

The separator has materials and joining techniques suitable to withstandpressures encountered at wellheads. Nominal wall thickness isapproximately 3 inches but this is not a limitation and the separatorcan be constructed with wall thickness to correspond to specificpressures encountered at point of use. The wall thickness will need tobe in a range that can be sourced, manufactured and fabricated. The wellpressure will range from what is commonly known as shut-in pressure asthe highest to zero and can range from lower than 500 psi to more than20,000 psi. The vessel wall thickness, joining specifications, fixturingand fitting will be sized to accommodate specific pressures and oneskilled in the art will recognize that changes to accommodate pressuredoes not change the operation of the separator or the invention and thatdifferent use locations will correspond to different working pressures.

FIG. 4 provides an additional illustration of the exterior of separatorvessel drawing attention to the tangentially arranged inlet system, thatis comprised of connection surface 40, with connection points 42 throughinlet tube interior 41, that is arranged substantially above themid-plane 37 of the separator. This is only one embodiment of a largenumber of connection schema and should not be considered a limitation.The location and arrangement of the fluid inlet offset is determined bythe separator dimensions, fluid characteristics, pressures andviscosities of a given well, and is not a limitation. Fluid and solidparticle components are delivered to the separator vessel by apparatus,tubing and equipment conventionally used from a wellhead. Said separatorcan be supported directly on the valves, manifolds and fixtures belowthe separator or can be supported by a stand, by legs structurallyattached to the separator or by chains or cables that support theseparator or by other support means. The method of support does notchange the function of the separator as one skilled in the art willrecognize. The separator can be on a mobile skid, or other systemdesigned to be transported from site to site as well as mounted in amobile environment as a trailer or truck and one skilled in the art willrecognize this is not a limitation on the function of the invention. Onehaving ordinary skill in the art will understand that the fixturing andmounting does not change or augment the essentials of operation. Fluidis directed essentially from the wellhead to the separator. Manifolds,tubular structures and valves as well as other systems encountered atthe well site may also be in-line or in conjunction with the separator,and one skilled in the art will understand those components will notchange the operation of the separator. Solid particles are removedthrough port 33 at the lower portion of the vessel. During operation,the extraction area is sealed to allow the separator to operate atconventional operating pressures encountered at the wellhead.

Particles collected can be removed by opening to allow extraction of thesolids when pressure is isolated from the sphere by valve 22 and throughport 32. The upper region of the sphere comprises a fixturing system andmounting surface 38 to maintain and support the filter system and thefluid exit port 39. After the fluid and solid particles have entered theseparator through port 11 and have been acted on by the separator thesolid materials are predominately stationary in the lower regionawaiting collection and removal through opening 32. Lighter particlesthat remain entrained in the fluid are removed by the filter elementthat can be located either internal to the sphere or external. Thefilter element is arranged to be removed for cleaning, servicing andreplacement. The vessel fittings and fixtures for use in conjunctionwith the filter comprises a threaded opening that allows forinstallation and removal using threads or clamps or bolts or otherfixturing schema. It will be recognized by one skilled in the art thatthe specific means for attaching a filter is not material to separatorperformance and a wide range of fixturing systems can be used with nochange in the inventive concept.

FIG. 5 shows a top down view cross section of the vessel more or lessabove the midplane, highlighting the tangential inlet port flange 30,inlet tube 31 and separator penetration 13, that is arranged primarilyabove the horizontal mid-plane. A solid particle component that entersthe separator will contact the internal surface of the separator, forexample, in or around region 50. Said particle will move generally inpath 51.

FIG. 6 shows a generalized section of the separator. Particle 60 movesboth around the sphere and generally will be move to larger sphereradius during said transit. Because particle 60 is introduced generallyabove the midplane, the particle will move to regions of larger internaldiameter. Particle 60 will travel through direction 61, in contact withvessel interior surface 35, as said particle moves at first to largervessel diameters by means of traveling along expanding wall diameter 62,until particle is substantially at a midplane, said midplane is theregion of maximum vessel diameter. As particle 60 moves to regions oflarger diameter, the momentum of said particle will decrease andadditional forces including but not necessarily limited to gravity willcontribute to said particle moving to substantially lower regions ofseparator. As particle moves to lower regions of separator,progressively less energy from moving fluid is imparted to particle.Eventually a preponderance of particles will become more or lessstationary and collected at the lower region of separator.

FIG. 7 schematically shows two halves of the sphere with a welding bevel70 arranged substantially at the midplane of the separator comprised ofone side from upper chamber half 71 and one half of the welding bevelfrom lower chamber portion 72. For manufacturing, the vessel iscomprised of two or more sections that are welded or bolted or otherwisejoined to provide an essentially featureless vessel interior. While FIG.7 schematically indicated two halves 7l and 72, and a welding bevel 70,one skilled in the art will recognize that more than two pieces can beassembled to create a separator vessel and that methods other thanwelding can suitably join the sub-systems including but not limited tobolting, threading, friction fitting, press fitting, riveting, or othermethods of suitable joinery. In addition, fabrication methods mayinclude construction from a substantially single piece of material.Method of fabrication is not a limitation and one skilled in the artwill recognize that the invention is independent of method ofconstruction and fabrication.

FIG. 8 shows a velocity profile where there is a region of low angularvelocity A for fluid and particles close to the center of the chamber, aregion B of greater angular velocity as the particles are less close tothe center of the separator, a region of decreasing angular velocity Cand a region of the greatest angular velocity D.

In general, the greater the radial location of a solid particle thegreater the angular velocity and the greater the angular momentum ofeach solid particle. Small scale deviations to this general notion doesnot change the operation of the separator and one skilled in the artwill recognize these variations do not change the operation of theseparator and are not a limitation. The angular velocity will bedetermined by the inside diameter of the sphere, the pressuredifferential between inlet pressure and vessel pressure, the velocity ofthe entering fluid and solid particle components, and the viscosity ofthe mixture of fluid and particles. Perturbations to parameterscomprising the said diameter, inlet pressure, fluid velocity, andpressure differential will be apparent to one skilled in the art to notbe a limitation and to not change the inventive concept. The angularvelocity will in general cause all parts of the fluid and particles tobe subjected to forces including a centrifugal force that will generallycause a migration to the larger radius trajectory closer to the wall ofthe interior sphere. In addition, because the inlet is above thehorizontal mid plane, particle solids will move lower in the chamber dueto gravity and because of other apparent and real forces. As theparticles drop due to gravitational effects, the inside of the spherediameter will increase due to the inlet being above the mid-plane andthe fluid velocity will decrease and this in turn will increase thelikelihood of a particle settling at the bottom of the chamber.Particles that are not substantially entrained by the fluid will migrateto the lower region of the sphere and will collect. Less massiveparticles will remain entrained by the fluid flow and those that are notseparated by the action of other forces including gravity andcentrifugal force, can be mechanically separated by a mechanical filter.

In addition, FIG. 8 also shows the angular velocity is lower for smallradii and greater for large radii. The lower angular velocity is foundtoward the middle of the chamber.

FIG. 9 shows one embodiment of a mechanical filter element. Detail ofsaid filter include connecting threads 90, exterior screen 91, end tubeplate 92 and internal frame 93.

FIG. 10 shows the interior of the vessel 100 as being comprised of anessentially continuous, essentially spherical and essentiallyuninterrupted interior surface. FIG. 10 also indicates the fluidentrance aperture 101 on the separator interior surface. Said interiorsurface comprises a regular surface and openings for functionality.Openings include but are not limited to a fluid entrance, a materialremoval system aperture 102 and an exiting fluid penetration 103 toallow the material to exit the separator. There may be otherpenetrations including but not limited to pressure sensors, fluidvelocity sensors, additional inlets, additional solids removal ports andadditional filter fixtures. One skilled in the art will recognize thatadditional port openings will not substantially affect the separatorfunction. FIG. 10 also shows a schematic of collected solid particlecomponents 104 substantially at the bottom of the separator. The figurealso shows the exterior surface 105 that may be spherical but may beother geometries as well. The figure also shows a possible particle pathof motion 106 indicating among other motions a path to the lower portionof the separator. Various coupling and connection methods 107 may beused but is not a limitation to the function of this invention. The exitfor fluid 108 is essentially at the top of the device and may beparallel to the midplane to allow for connection to subsequentapparatus.

FIG. 11 shows detail of the filtration unit 112 including a filterelement 110 and particles 113.

FIG. 12 shows a representative particle 60 proximate to interior surface34 with representative actual and apparent forces indicated comprised ofgravity, the Coriolis force, centrifugal, and centripetal forces. Duringoperation, high pressure fluid and solid particles components enter theseparator interior tangentially and substantially above the horizontalmidplane and begina generally circular and essentially discotic path inthe separator interior, caused by the essentially spherical shape of theseparator interior. A particle 60 will follow a trajectory 61,influenced by the interior surface 34 of the separator and thepreviously named forces. This more or less discotic trajectory issubstantially parallel to the device midplane, and more or less parallelto the earths local surface. The rotational motion of said particlecauses angular momentum as represented in FIG. 8 to be imparted to theparticles and fluid. Forces comprised of gravitational force andapparent forces centrifugal and Coriolis are indicated schematically, inorder to represent some of the potential actions on the solid particlecomponent. g. In this case, a particle has mass m, and the weight is theproduct of mass and gravitational constant In this schematicillustration, F_(g) is the force due to gravity and is commonly thenegative product of mass and gravitational constant or −mg, F₁₀₇ is thecentrifugal force and is the vector multiplicative product of the massand square of the velocity vector divided by the radial distance ormv²/r where bold case indicates a vector quantity, and F_(c) is theCoriolis force and is the vector cross product of the angular velocityvector ω and linear velocity v, increased by the negative of twice themass, (−2 m) or −2 m(ω x v) where x is the vector cross product.

FIG. 13 shows the separator 130, two external filters 131 and aplurality of valves 132, 132′.

While the invention has been particularly shown and described withreference to preferred and alternate embodiments, it will be understoodby those skilled in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinvention. By way of example, the fixturing and fitting to support thevessel may be changed without changed the invention. The filter elementfixturing and fitting as well does not change the basic inventivenature.

REFERENCES CITED

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We claim:
 1. An apparatus for separating solid particles from a movingfluid comprising: a) a vessel comprising: i) an internal surfacecomprising a substantially spherical interior region, said interiorregion allowing a moving fluid stream comprising solid particlecomponents to be introduced therein; ii) an inlet port in said vesselallowing introduction of said fluid stream; iii) an outlet port in saidvessel allowing exit of said fluid stream; and iv) a drain port in alower region of said vessel that allows removal of the solid particlecomponents.
 2. The apparatus of claim 1., further comprising a filter,located either internal to said vessel, at the outlet port, or near theoutlet port, wherein the filter removes at least a portion of anyremaining solid particle components in the exiting fluid stream.
 3. Theapparatus of claim 1., wherein the internal surface is a regularsymmetric shape comprising a region that is substantially spherical.